Contents |
What Everyone Who Wants to Send Email From Their Server Needs to Know
There are a few things that you just need to do/know if you are going to be a mail server. But how are you going to know these things unless someone tells you?
- Ensure your hostname is set.
- Setup a PTR that matches the hostname of your server.
- Mail providers will see your message as spam if you do not!
- Setup a SPF record for every one of the domains on the server.
- Spammers can use your domain to send spam if you don't, and other providers (like hotmail) make this mandatory.
- Submit your SPF to microsoft's senderID program if you are having trouble sending to hotmail. (http://microsoft.com/senderid)
How Email Works
Mail servers communicate to other mail servers by connecting to their port 25 (smtp). A piece of mail comes in on that port, is usually scanned for spam, and then delivered to the inbox. Then the user will use either IMAP or POP to log into the server and download that mail.
Stopping Outgoing Spam
In general, having good overall server security will stop your server from being compromised and stop it from sending spam. Other good practices include:
- Actively monitoring your server with top, looking in the mail queue, etc.
- Using php-suexec to see which user might be using php to send spam.
- Looking into the mail queue to try to find what user is sending the spam, and then disabling it.
How to get off of a black list
Believe it or not, most blacklists have a TTL (Time to live). If you don't do anything, most of the time the case will resolve itself. There are some blacklists, however, that do require manual requests for removal. You will have to investigate how to get off the particular blacklist you are on.
Here is the catch: Your server has to not be sending out spam in order to get off the blacklist (of course). Don't expect to be able to get off the list if the problem isn't fixed.
Links to Some Blacklists
- http://mxtoolbox.com Allows lookups on multiple blacklists at once
Setting up SPF records in cPanel
Setting up SPF records in cPanel
Setting up SPF records in Plesk
Setting up SPF records in Plesk
